Tunnel lining and method of forming the same



, K. C. BELLQWS Oct. 14, 1947.

' TUNNEL- ILIINING AND METHOD OF FORMING THE SAME Filed Sept: 12, 1945 Patented Oct. 14, 1947 UNITED STATES PATENT OFFICE TUNNEL'LINING' AND METHOD OFFORMING' THE SAME Kenneth C. Bellows; Sheridan Wyo... Application September 12, 1945;SerialNo; 615 ,746

1. .Claim. 1.

Thisinvention relates to improvements in and methods of formingtunnel linings, and more par-.- ticularly to linings for aqueducts and the like.

It is. conventional practice in constructing tunnels-t provide a. concrete lining around the entire periphery thereof. Such lining providesreenforcement for the roof of the tunnel, preventing cave-insv and, in the case of aqueducts, such liningshave the additional functions of preventingcontamination and loss of the water by seepage and promote easy flow of the water through the. tunnel. Such linings have heretofore been formedin the following manner. The base or invert which may extend up to about 45 on eith'erside is poured and after the concrete has set, rails are laid, or they may be embedded in the concrete during pouring, to facilitate delivery ofnmaterials for the balance of the lining. Forms extending around the balance of the periphery of the tunnel are then placed in position with their bottom edges resting on the upper edge of the base or invert. These forms are about to feet-in length. Since the rock and strata through which the tunnels are bored tend to breakdown unevenly, there may be quite high gapsaround and above these forms so that it is necessary to deliver" the grout behind the forms underconsiderable pressure to force it upwardly to.fill such gaps. This in turn necessitates the placing of bulkheads at each end of the forms so as to contain the grout therein. Due to the unevenness of the walls, these bulkheads must be painstakingly faces and then calked. In addition, considerable shoring is required to hold such forms in the desired position. Making these bulkheads and shoring therform's'requires a great deal of highly skilled hand labor and adds considerably to the cost of the tunnel lining. In addition to the expense; such operation is undesirable due to the discontinuity of the operation of placing a form, filling grout between the form and the tunnel wall, and then ceasingithe pouring until another form has been set in position and readied for pouring. Since the mixers and pumps are thus idle for considerable periods, they must be cleaned after each form is filled to prevent any grout beoming set therein while the next form is being placedin position. I

It'is accordingly an object of the present invention to overcome the foregoing disadvantages and to provide a method of forming tunnel linings which is considerably cheaper than present methods.

It is another objectto provide a method of pattern-cut'to fit the wall suriormingtunnel linings the concrete grout continuously;

It is 1awhich is simple in designand-rugged-and durable in impervious concrete tunnellining.

Thezforegoingand furtherobjects will be ape 1 parent from the-specification .and1drawing.;Where-.

Figure 3 is across section'of a. suitable form for-casting the arch or shell members;

Figure-4 -.is :a cross: section of an arch, or shell member of my invention;

Figure 5 is an enlarged or base; and" tween the ends of arch'or'shell members.

Referring more. particularly to the drawing, the numeral 2 designates the bore of the tunnel. .in-which aconcrete base or invert 4.has been.-

continuously poured;- Disposed on the invertA- are shell-liners -or arches aformedof- Portland:

cement or other suitable plastic, which have a tongue: and groove connection 8;at their upper. edges. Theends of the shell. members .mortar or 'suitable -calking material M asafin-e ishing step in the formation of the tunnel lining; The loweredge 0f the shells 6 and the outer edges:

4a, of the .invertlare shown in detail in Figure 5.

A smooth bearing-portion "i is-provided at-.the-.-

outer portion of the-invertqwithan upstandingi shoulder l8 which may have a-beveled upper edge.

with a-smooth lower 20. The shells are cast surface 22' to rest on the bearing surface I6; and an adjoining; shoulder 24 which is beveled as at 26; complementary-to the bevel 20:: Aisealing pad 28 of impregnated asbestos or the like may be disposed between the shoulder portions l8 and 24 of the invert and shells, respectively. This provides an inwardly opening groove 30 which, like the end joint, may be filled with morwhich permits pouring i use. It is a still further object'to'provideabhighly;

detail ofthe joint be-.' tween the arch or shell 'membersand theiinvert 6--arezbev:-- eled as at lilzas shown more clearly in Figure 6..

as a finishing lining.

permits a plurality of shells to be placed in position between the point of discharge and the placing equipment. As shown-in Figure 1, five pairs of shells are provided ahead of the point of discharge 40 of the grout. The number of shells required of course depends on their length and the heighth of the tunnel. In be stated that the length of the pipe 36 is at least long enough to permit four feet in length of the liner to be positioned for each foot in heighth of the tunnel, plus room for an additional pair of shells to be erected as the placing equipment 38 retreats. This permits the lining operation to be carried on continuously since, as the backfill 34 behind one pair of shells is being made, an additional shell is being erected adjacent the placing equipment.

As shown in Figure 1, the end of the pipe 36 or point of discharge 40 is maintained a considerable distance behind the downward fiow of grout so as to provide suificient pressure to force general. it may the grout upwardly into gaps, such as illustrated The shells may be cast on a form 50 such as is shown in Figure 3. It is understood that the shells are cast on right and left hand forms so that proper tongue and groove, and inwardly opening grooves, are obtained. The shells are preferably formed of a rich, rather dry mix of cement to obtain sufiicient strength with a thin cross section and should be vibrated during casting to insure solid walls and a smooth inner surface 55. Such smooth inner surface tends to promote the easy flow of fluids through a tunnel lined in accordance with the teachings of my invention, Despite the use of a rich mix for the shells, the total amount of Portland cement usedis not increased thereby, since a leaner mixture of cement may be used in the backfill 34 and sumcient strength obtained by reason of the backfill being poured continuously. Moreover, the con-.

tinuous pouring of the backfill forms a continuous monolithic backfill which has no joints and is therefore quite impervious. Calking of the shell liners, as described hereinbefore, also increases the imperviousness of the lining.

In forming tunnel lining, as herein described, the bore 2 of the tunnel should, in most instances, be completed before lining operations are started. The invert 4 is then poured and, if the height of the tunnel is sufficiently high to make it desirable, side walls may be formed. Lining operations are then begun by placing the desired number of the arch forming shells or liners in position as before described. The outer end of the outer pair of shells may then be calked or bulkheaded or this may result from a facing being formed at the entrance to the tunnel. Grout is then forced behind the arch forming shells in a continuous pouring operation. As the placing newly erected arch equipment 38 is withdrawn, additional pairs of arch forming shells are erected so that the desired number of shells to keep the total length thereof in front of the point of discharge is greater than a total of four feet in length for each foot of heighth of the tunnel. Thus the erection of the arches never interferes with the pouring of the monolithic backfill. In average tunnel operations, the lining will proceed from one end towards the other end and the arches and other material will be brought in through the end of the tunnel which has been lined. In this Way, the delivery of the arches cannot interfere with the. movement or operation of the placing equipment. However, in the case of large diameter tunnels, it might be desirable to start the lining operations in the midportion of the tunnel and work away from such point towards both portals simultaneously.

While I have shown and described one specific embodiment of my invention, it will be understood that this embodiment is merely for the purpose of illustration and description and that various other forms may be devised within the scope of my invention, as defined in the appended claim.

I claim:

A method of forming a lining in a tunnel bore comprising forming a base, placing a plurality of longitudinally aligned sectional arches on said base, the length of said erected arches being at least four times the height of the tunnel bore, forcing concrete grout behind said arches to form a backfill, maintaining the point of discharge sufiiciently back of the poured material to obtain sufficient back pressure to force the concrete grout upwardly to completely fill the space between the arches and the top of the bore, erecting additional arches as the concrete grout is forced behind the previously erected arch sections to keep the length of the erected arches in front of the point of discharge a distance of at least four times the height of the bore and continuing forcing the concrete grout behind the sections whereby the erection of the arches and the forcing of the concrete grout backfill stantially uninterruptedly to thereby obtain a substantially continuously poured 'monolithic backfill.

KENNETH C. BELLOWS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,715,125 Hackley June 4, 1929 1,642,709 Zucco Sept. 20, 1927 1,216,317 'Hirsh, Feb. 20, 1917 FOREIGN PATENTS Number Country 9 Date 471,875 Germany 1929 473,255 Germany 1929 OTHER REFERENCES Engineering News-Record, June 11, 1936, pages (Copy in Division 33.)

therebehind continues sub-' 

